All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If you did that before reaching puberty, then you bear no sin because you were not accountable, and if it happened after puberty - while you were ignorant of its prohibition - then we hope that you bear no sin for it. And according to the estimation of your sin by that, it is sufficient for you to repent between you and Allah, and Allah is forgiving and Merciful. And there is nothing to worry about or the need to ask forgiveness from your brothers.
Instead, they should not be informed of that, nor should anyone else be informed of it, so conceal yourself with Allah’s concealment over you and do not expose yourself. And forget what has happened and do good in what is to come. And there is no effect on what happened to the validity of the marriage.
We ask Allah Almighty to make marriage easy for you and to bless you with guidance, piety, chastity, and wealth.
Allah knows best.